Underwater light quality selection of invasive and native Myriophyllum species in China: Invasive species prefer blue light, while native species prefer red light

Light quality is an important factor for submerged macrophytes. However, differences in the selection of underwater light quality between invasive and native Myriophyllum species submerged macrophytes remain unclear. The effects of white light and different red-to-blue ratios (R: B=1: 8, 1: 4, 1: 1, 4: 1, and 8: 1) light on the morphological, photosynthetic, and stoichiometric traits of the invasive species Myriophyllum aquaticum ( M. aquaticum ) and the native species Myriophyllum spicatum ( M. spicatum ) were studied by a control experiment. More red light (R: B=4: 1, 8: 1) significantly promoted roots elongation, aboveground biomass accumulation, and phosphorus (P) synthesis. However, more blue light (R: B=1: 8, 1: 4) was conducive to the synthesis of the three photosynthetic pigments in M. aquaticum . Blue light directly affected the morphological traits of M. aquaticum . Thus, it had greater plant height, more leaves and branches, and significantly greater biomass accumulation under more blue light. However, excessive blue light inhibited the root growth of the two Myriophyllum species. In contrast to M. aquaticum , under more red light, total phosphorus and total organic carbon content of M. spicatum were higher, the utilization efficiency of nitrogen and phosphorus was higher, and the growth of M. spicatum was better. Our study shows that it is recommended to preferentially introduce the native species M. spicatum for the treatment of eutrophic lakes dominated by red light. • White light, different ratios of red and blue light were applied to the study. • More blue light promoted M. aquaticum but inhibited M. spicatum . • More red light favoured root elongation, aboveground biomass, and P synthesis. • Invasive and native species exhibited different response mechanisms to light quality. • M. spicatum is recommended to preferentially introduce to treat eutrophic waters.